Sequence changer



Feb. 25, 1964 A. D. SULLIVAN 3,122,003

SEQUENCE CHANGER Filed March 13, 1962 CONOINSEK CONDENSER INVENTOR. 44 50 0. 5044/1/44! M 4 TI'OlP/VEV United States Patent Ofilice 3,l22,dd3 Patented Feb. 25, 1984 3,122,003 SEQUENCE CHANGER Alfred D. Sullivan, Dearborn, Mich., assignor to American Radiator & Standard Sanitary Corporation, New York, N.Y., a corporation of Delaware Filed Mar. 13, 1962, Ser. No. 179,359 1i) Claims. (Cl. 62-157) This invention relates to control devices, as for example devices which control the operation of refrigerant circulating mechanisms in refrigeration machines.

One object of the present invention is to provide an arrangement of control devices which will automatically alternate the operation of the various mechanisms controlled thereby during successive operational cycles.

In a particular environmental use of the invention it is an object to provide a control system for a refrigeration machine wherein the machine is provided with two refrigerant compressors, the control system being operative to alternate the sequence of operation of the compressors during successive refrigerant cycles so that each compressor has approximately the same Wear after prolonged service.

A general object of the invention is to provide a sequence alterin control which is relatively simple and which requires minimum electrical harness.

Other objects of this invention will appear from the following description and appended claims, reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

In the drawings:

The single figure is a schematic showing of a refrigeration machine having one embodiment of the invention incorporated therein.

Before explaining the present invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and or" being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

Referring to the drawing there is shown a refrigeration machine having an evaporator shell 10, a pair of condensers 12 and 14, and a pair of compressors 16 and 18. Each compressor is driven by a power device shown as an electric motor as or 22, the arrangement being such that operation of a particular motor causes refrigerant to be circulated past an expansion valve 24 or 26, through the evaporator shell and thence into one or the other of the suction lines 28 or 3%, depending on which the compressor motors is operating.

In the illustrated machine the evaporator shell is provided with a series of connected water tubes 32 which discharge chilled water into a discharge conduit 34 for use at remote locations (not shown). The general objective is to provide a supply of chilled water in conduit 34 having a constant temperature, as for example forty-two degrecs. In order to achieve this objective without excessive hunting the mechanism includes two compressor-condensers as shown. When the water temperature in conduit 3-:- is only one or two degrees above the desired value, one of the compressors is put into operation by low temperature thermostat 40, but in the event that a large demand should raise the temperature of the water in conduit 34 more than one or two degrees above the desired value then the second compressor is put into operation by high temperature thermostat 42. In this way the amount of refrigerant circulated through shell 10 is to a certain extent proportional to the demand for refrigeration such that excessive hunting of the control circuit is avoided.

In order to prevent excessive wear on one or the other of compressors 16 and 18 it is desirable that during successive refrigeration cycles the order in which the compressors begin to operate is reversed, i.e., during one cycle compressor 16 acts as the lead compressor under the control of thermostat 49 and during the next operating cycle compressor 18 acts as the lead compressor. The alternate lead compressor operation is accomplished by the diagrammatically illustrated sequence changing devices designated generally by numerals 36 and 38.

Current is supplied to devices 36 and 38 through the conventional condition responsive thermostats 40 and 42. As shown in the illustrative drawings each thermostat includes a thermostatic bulb 44, a length of capillary tubing 46, a casing 48, and a diaphragm 50 arranged on temperature increase to move switch arm 52 or 54 to the circuit-closed position wherein current from the power line 56 is fed to one or the other of lines 558 and 60. The other power line is denoted by the numeral 62.

Line 60 connects with the terminal 64 and a three-terminal stepping switch having second and third terminals 66 and 68. As shown in the drawing terminal 64 continually contacts the electrically conductive switch element disc 76 which is carried on the rotary non-conductive disc 72. A ratchet 74 is secured to disc 72 so that its teeth are engaged by the operating arm 76. Back and forth movement of arm 76 is accomplished by the armature 73 which may be swingably operably mounted on a pin 77 carried by the base 75 In order to operate the armature '78 there may be provided a solenoid 82, the arrangement being such that energization of the solenoid by current flow in line 60 causes armature 78 to pivot rightwardly about its mounting on pin 77 so as to move ratchet 74 counterclockwise a distance of one ratchet tooth. When solenoid $2 is later de-energized a con pression spring 38 moves the armature '78 and arm 76 back to the illustrated positions. A suitable pawl (not shown) may be provided for preventing reverse rotation of ratchet 74-.

Sequence changing device 3:5 is of generally the same construction as device 38, and similar primed numerals are therefore employed for corresponding parts. It will be noted that both solenoids 82 and 82 are energized from line 6i? which leads from thermostat 40. There fore when switch arm 54- is closed both solenoids are energized to move the respective ratchet 74 or 74' counterclockwise one-tooth distance. As soon as permitted by time delay relay 98 current will be fed to one or the other of the compressor motors, depending on the positions of the respective discs '76 and 7d. The respective discs are differently disposed with relation to their associated contacts so that during one operating cycle disc '79 energizes motor 20 while disc 7% energizes motor 22 and during the next operating cycle disc energizes motor 2t) while disc 70' energizes motor 22. Each disc constitutes a double throw switch since it is arranged to complete a different circuit in each of its two positions.

Time delay relay $8 as shown in the illustrative drawings comprises a switch arm 1% arranged so that after the low temperature thermostat dd has supplied current to solenoid 82 the armature 78 operates arm 1% to complete the circuit between lines 97 and 99. The purpose of time delay relay 98 is to delay energization of motors 2t and 22 until after solenoids 82 and 82 have advanced discs 74 and 79' to their new positions at the beginning of each operating cycle.

In one particular environment of the invention thermostat 40 is adjusted so that arm 54 closes when the Water temperature in conduit 34 is forty-five degrees and opens when the water temperature drops to forty-two degrees.

High temperature thermostat 53 is arranged so that switch arm 52 thereof closes at forty-six degrees and opens at forty-three degrees. Thus, if there is a moderate demand for chilled water only the thermostatic arm 54 will be closed, in which event only line 6% will be energized, i.e., line 53 will be a dead line, and no current will flow to either of the terminals 66 or 68'. Assuming under such conditions that disc 70 is initially in its illustrated position, current from line 6i) will energize coils 82 and 82', whereupon one of the projections of disc 70 will connect with terminal 63 so that at a suitable time delay (as determined by delay means 93) motor 22 will be energized for causing a moderate how of refrigerant past the expansion valve 26 and into the evaporator shell 19. Motor 22 will continue to operate until thermostat at is sat1sfied, whereupon switch arm 54 will open to interrupt the flow of current to motor 22 and the two solenoids. Springs 88 and 88 will then reset armatures 78 and '78 to their illustrated positions.

Assume however that, in spite of the flow of refrigerant caused by operation of compressor 13, the temperature of the conduit 34 liquid continued to rise to forty-six degrees or higher. In such event switch arm 52 would close to energize line 58. Current would thereupon be supplied to terminal 66, thence to lines 91 and 92, and thence to motor 29 so that an incrcmed refrigerant fiow would take place through shell 10.

On the next call for cooling by thermostat 40 the discs '70 and 70' will be advanced counterclockwise one-tooth distance so that the next projections thereon are engaged with the contacts 6-5 and 68 (as shown). If only thermostat 49 is calling for coolant only motor 26 will be en ergized, whereas if thermostat 42 should subsequently call for coolant compressor motor 22 would then be energized.

it will be seen that during one cycle compressor 18 acts as the lead compressor to satisfy the low cooling demand, whereas on the next operating cycle compressor 16 acts as the lead compressor to supply the low cooling demand. The lead compressor works for longer periods, and by having the two compressors take turns as the lead compressor the wear on each compressor is made approximately the same. Thus, both compressors last for a relatively long period of time rather than having one cornpressor wear out prematurely.

The invention may be practiced without using the specific arrangement shown in the drawings. For example, both discs 72 and 72' may be driven from one solenoid-ratchet arrangement, thus dispensing with the extra solenoid-ratchet assembly. If desired a spring return motor or other power device can be substituted for the illustrated solenoids.

In the illustrated arrangement the sequence changing operation is performed at the beginning of each operating cycle. However the sequence changing operation can if desired be performed at the end of the operating cycle, as by altering the manufactured relationship between arm 76 and ratchet 74.

The drawings show the invention as applied to a refrigeration environment. However it is believed that the invention could have application in certain heating environments. In the appended claims the term temperature conditioning mechanism is therefore employed to apply to both cooling and heating mechanisms. The term condition responsive control device is used in the claims to denote either the cooling thermostats 4t) and 42 or the heating thermostats which would be employed in a heating environment.

I claim:

I. in combination, a plurality of condition-changing electrical power devices; a plurality of condition responsive control devices adapted to individually control the operation of individual ones of said power devices; and sequence-changing means interconnected with the control devices and power devices so that during one cycle a given power device is controlled by one of the control devices and during the succeeding cycle the given power device is controlled by another control device; said sequence changing means including first and second switches operably connected so that during one cycle the first switch controls current flow to the given power device and the second switch controls current flow to the other power device, and during the succeeding cycle the first switch controls current flow to the other power device and the second switch controls current flow to the given power device.

2. In combination, two electrically-energized conditionchanging power devices; two condition responsive switches; and sequence changing means interconnected with the power devices and switches so that during one cycle a given power device is under the control of one of the switches and during the succeeding cycle the given power device is under the control of the other switch; said means including a switch arranged during one cycle to control current flow to the given power device and during the succeeding cycle to control current ilow to the other power device.

3. In a refrigerat ng system having two separate power devices for circulating refrigerant therethrough; two separate condition responsive devices calling for different refrigerant flows through the system; and sequence-changing means interconnected between the power devices and condition responsive devices for alternating the sequence of energization of the power devices during successive refrigerant cycles; said sequence-changing means including two switching elements movable simultaneously between different device-energizing positions.

4. In a temperature conditioner mechanism having two separate electrical power devices for circulating the conditioning medium therethrough; two separate temperature responsive devices operating to successively call for different conditioning medium flows until individually satisfied; and means interconnected between the power devices and temperature responsive devices for alternating the sequence of energization of the power devices during successive operating cycles; said sequence-altering means comprising first, second, third and fourth electrical terminals, and switch elements associated therewith so that during one cycle the first and third terminals control current flow to individual ones of the power devices, and during the succeeding cycle the second and fourth terminals control current flow to individual ones of the power devices.

5. In combination, a refrigeration mechanism having two power devices for circulating refrigerant therethrough; first and second thermostats responsive to conditions controlled by the refrigeration mechanism for energizing the power devices at different refrigeration demands, and control means interconnected with the thermostats and power devices so that during one cycle the first and second power devices are controlled by the first and second thermostats respectively, and during the succeeding cycle the first and second power devices are controlled by the second and first thermostats respectively; said control means having first and second power device-controlling terminals operatively associated with the first thermostat, and third and fourth power device-controlling terminals operatively associated with the second thermostat, whereby during one cycle the power devices are operated by current controlled by the first and third terminals, and during the succeeding cycle the power devices are operated by current controlled by the second and fourth terminals.

6. In combination, a refrigeration mechanism having two electrically energized power devices for circulating refrigerant therethrough; first and second thermostatic switches responsive to conditions controlled by the refrigeration mechanism for energizing the power devices at different refrigeration demands; and electrical control means interconnected with the thermostatic switches and power devices so that during one cycle the first and second power devices are controlled by the first and second thermostatic switches respectively, and during the succeeding cycle the first and second power devices are controlled by the second and first thermostatic switches respectively; said electrical control means comprising two device-energizing switches of the double throw type, one under the influence of the first thermostatic switch and the other under the influence of the second thermostatic switch.

7. In combination, a refrigeration machine including an evaporator shell, conduit means for circulating heat exchange fluid through said shell, and two separate electrically-operated devices for circulating refrigerant into and out of the shell to cool the heat exchange fluid; first and second thermostatic switches responsive to the temperature of the heat exchange fluid leaving the evaporator shell; and control means including cyclically-operated switch means interconnected with the thermostatic switches and refrigerant-circulating devices so that each refrigerant circulating device is under the control of a difierent thermostatic switch during successive refrigerant cycles; said control means comprising a power means for moving the cyclically-operated switch means at a predetermined time in each cycle, and means for automatically opening the circuit through the cyclically-operated switch means while the switch means is undergoing movement.

8. In combination, a refrigeration machine including an evaporator shell, conduit means for circulating heat exchange fluid through said shell, and first and second separate electrically operated devices for circulating refrigerant into and out of the shell to cool the heat exchange fluid; a first thermostatic switch operating in a relatively low temperature range of the heat exchange fluid; a sec ond thermostatic switch operating in a relatively high temperature range of the heat exchange fluid; and sequence-changing means interconnected with the thermostatic switches and refrigerant-circulating devices whereby the respective refrigerant circulating devices are under the control of different thermostatic switches during successive refrigeration cycles; said sequence-changing means comprising two energizing paths for each circulating device, and switch means arranged so that two of the paths are usable in one cycle and the remaining two paths are usable in the succeeding cycle.

9. In combination, first and second temperature conditioning mechanisms; first and second thermostats respon- 4 sive to different temperature levels controlled by the conditioning mechanisms; first and second switches, each having a first terminal connected to a respective one of the thermostats, each having a second terminal connected to one of the conditioning mechanisms, each having a third terminal connected to the other conditioning mech anism, and each having a switching element arranged to connect the first terminal with the second and third terminals at alternate periods; said switches being arranged so that the second terminal of one switch is connected with its switching element while the third terminal of the other switch is connected with its switching element, and vice versa; and power means controlled by the first thermostat for altering the position of each switching element during successive operating cycles, whereby during one cycle the first thermostat controls the first conditioning mechanism while the second thermostat controls the second conditioning mechanism, and during the next cycle the first thermostat controls the second conditioning mechanism while the second thermostat con trols the first conditioning mechanism.

10. In combination, first and second refrigerant compressors and motors therefor; first and second thermostats responsive to different temperature levels controlled by the compressors; first and second switches, each having a first terminal connected to a respective one of the thermostats, each having a second terminal connected to one of the compressor motors, each having a third terminal connected to the other compressor motor, and each having a switching element arranged to connect the first terminal with the second and third terminals at alternate periods; said switches being arranged so that the second terminal of one switch is connected with its switching element while the third terminal of the other switch is connected with its switching element, and vice versa; and power means controlled by the first thermostat for altering the position of each switching element during successive refrigeration cycles, whereby during one cycle the first thermostat controls the first compressor while the second thermostat controls the second compressor, and duing the next cycle the first thermostat controls the second compressor while the second thermostat controls the first compressor.

References Cited in the file of this patent UNITED STATES PATENTS 2,177,602 Spaan Oct. 24, 1939 2,237,304 Greenlee Apr. 8, 1941 2,776,543 Ellenberger Jan. 8, 1957 

1. IN COMBINATION, A PLURALITY OF CONDITION-CHANGING ELECTRICAL POWER DEVICES; A PLURALITY OF CONDITION RESPONSIVE CONTROL DEVICES ADAPTED TO INDIVIDUALLY CONTROL THE OPERATION OF INDIVIDUAL ONES OF SAID POWER DEVICES; AND SEQUENCE-CHANGING MEANS INTERCONNECTED WITH THE CONTROL DEVICES AND POWER DEVICES SO THAT DURING ONE CYCLE A GIVEN POWER DEVICE IS CONTROLLED BY ONE OF THE CONTROL DEVICES AND DURING THE SUCCEEDING CYCLE THE GIVEN POWER DEVICE IS CONTROLLED BY ANOTHER CONTROL DEVICE; SAID SEQUENCE CHANGING MEANS INCLUDING FIRST AND SECOND SWITCHES OPERABLY CONNECTED SO THAT DURING ONE CYCLE THE FIRST SWITCH CONTROLS CURRENT FLOW TO THE GIVEN POWER DEVICE AND THE SECOND SWITCH CONTROLS CURRENT FLOW TO THE OTHER POWER DEVICE, AND DURING THE SUCCEEDING CYCLE THE FIRST SWITCH CONTROLS CURRENT FLOW TO THE OTHER POWER DEVICE AND THE SECOND SWITCH CONTROLS CURRENT FLOW TO THE GIVEN POWER DEVICE. 